Your standard ATC size 2 and 1/2 by and a half this is completely the sender's choice of what they want to do as far as the theme the only requirement is that it must be black and white use your imagination and your creativity make it really good and well make sure it's something that you would love to receive includes some fun goodies or extras that's also black and white make sure you label the name of the swap in your username
I will angle if i have to